So this is my theory of how the Andalite three-name system works.
I hadn’t thought of an analogy between the Andalite and Roman naming systems.
I recognized the firstborn and father, secondborn and mother, share middle names pattern. So I figured that they were gender-neutral but not necessarily family names.
I also guessed grandparents had something to do with the last names. In my headcanon, males share a last name with their paternal grandfather, females with their maternal grandmother.
I figure a middle name matching another’s last name is a break in the pattern.
Yeah, canon rarely gives full names of immediate relatives, let alone extended family.